/Engine/Plugins/Experimental/TextToSpeech/Source/TextToSpeech/Public/GenericPlatform/TextToSpeechBase.h
Immediately speaks the requested string. If another string is being spoken by the TTS, the current string will immediately be stopped before the requested string is spoken. Note: Passing in long sentences or paragraphs are not recommended. Split the paragraph into shorter sentences and register with the OnTextToSpeechFinishSpeakingDelegate to pass in the next chunk.
void Speak ( const [FString](API\Runtime\Core\Containers\FString) & InStringToSpeak )